If you are a Karting fan you probably have an idea for what the perfect chassis would look like in your mind. Something lightweight of course but strong and durable, a material able to send the kart launching forwards without any kind of damage. Something like what is used by successful and professional race car teams like McLaren. Perhaps you dream of a kart that can take side turns at high speed without wheels lifting even a fraction off the ground, something that glides effortlessly much like you see in sci-fi movies like I Robot. With a perfect frame of course there are perfect tires that offer the best traction and excellent control on curves.
So lets get some perspective on what you need to know about Go Kart frames or the chassis as is it more professionally called. This is the most important part of the kart and how it is made and how well it is made will be pivotal in having a good go kart. The frame holds different components of the go kart together. It is welded using torsion bars, to get a stiff frame you have bars that are crossed together and are short. For a frame with more flexibility the bars are longer.
In early days stiffer and less flexible frames were the most commonly used ones in go kart designs. But these commonly broke down and often because they did not have the tire traction and suspension needed for stopping, turning and accelerating. You cannot compensate for a less than healthy frame by running on 2 cycle engines or 4. Without tire traction there is less stability on the frame from weight transfer that is not even. One side or even both can be ripped loose. Basically the frame dictates how successful the go kart is at moving whether it is zipping along on dirt, concrete or asphalt, and whether you are taking short turns or wider ones.
A lot of people see the frame as resisting the demands and force of the go kart as it accelerates forwards. But as well as that a well-built go kart frame needs to allow you to maneuver on the track particularly in the turns. How effectively and safely a kart turns right or left is dependent on how good a frame you have. When a go kart is made from materials and components that are cheaper the kart as a whole is weaker, there is drifting and sliding in turns, and sometimes even flipping. You want to side bite meaning the go kart stays on the track without sliding or lifting and that is not possible without the proper frame. In some cases poorly made karts can leave your control, or even shut off when the pressure to the engine is too much.
As mentioned what you need to know about go kart frames is that in order to maintain side bite and do well in turns you need a well designed chassis. These frames are made up of rear and front rails and the ends of the rails are called kingpin. Less side bite is often a result of having narrow rear rails, widths between 24 to 25 inches from one kingpin to the other. Standard go karts rarely go over 30 inches width rails. But understanding the dynamics of the rear and front rails can perhaps better be explained with this example. If you have two water containers, a 16oz water bottle and a two gallon jug and you pushed at both with a stick, which is more likely to tip? That would be the water bottle, as the gallon jug had a wider base or foundation so offered it more stability. The same principle applies to the rear and front rails.
Having the right frame for your go kart also will depend on what kind of surface you will be riding on. Dirt, concrete, asphalt, there are different surfaces to kart on and different frames that are better for each of them. For example on a dirt surface track the best frame would be one with a longer back rail and then short front one as dirt tracks put more stress on the front of the rail. Also if your back rail is too stiff the engines power can cut out when taking a turn. But for concrete and asphalt the reverse is true.
How well a frame performs is largely dependent on the go karts tire traction. Tires that are not well grooved to handle the surface, have low traction and do not stick to the ground well. This in turn causes the stiff frame to rattle and become damaged, and it also means the weight transfer through the kart is uneven. When that is the case you will not have the best control. For example just imagine you own two pairs of roller skates and one has wheels that are narrow at just half an inch and the other pair has wheels that are 3 inches. Which would you have better luck balancing on? Basically the better traction you have the more stability you have.
A big problem for go karters is having a frame that is still flexible but also lasts longer and is still durable. When you are pushing it through tough turns ans hard breaks, and hitting track walls every so often this can cause the frame to become distorted. A distortion cannot just be popped back into place and for this reason go karting experts say frames should be replaced annually. There are things you can do to maintain your kart and keep that flexibility for longer. For example taking the course backwards has a reverse effect shaping it opposite to how it would normally be shaped.
What you need to know about Go Kart frames is that flexibility is key. A stiff frame and high traction tires is not a good combination, it creates a lot of stress on curves and it turns too stiffly. On the other hand low traction tires can cause the weight transfer to be uneven and cause the frame to break apart. It is also important to consider what tracks you are racing on and what kind of go kart you are using, it is not a case of one frame suits all. And if you are racing on harder circuits your frame should be more flexible not less.